The present invention pertains to the field of the regulation of fluid being expelled from a surgical site. More particularly, the invention relates to a fluid flow regulator, which when used, regulates the flow of fluid from the surgical site and serves as a passive smoke evacuation system for a pressurized surgical site.
Minimally-invasive surgical procedures such as laparoscopic or endoscopic surgery have become increasingly common due to the fact that the procedures generally result in shorter recovery times, less side effects including secondary infections, shorter operating durations, and reduced costs. The term xe2x80x9cendoscopicxe2x80x9d as used herein encompasses arthroscopic, laparoscopic, hysteroscopic, thoracoscopic or any other similar closed surgical procedures performed with instruments inserted through small, artificially created openings or portals in the patient.
In conventional laparoscopic procedures, a first minimally-invasive surgery access port is formed in the patient""s abdomen using a Veress needle to puncture the lapra or abdomen. An insufflator gas such as carbon dioxide is injected into the abdomen to distend the pneumoperitoneum, thereby creating an air space or cavity in proximity to the organs on which the surgical operation is to be performed. The cavity provides the work space necessary for the surgeon to maneuver the surgical instruments and endoscope, which are typically introduced into the surgical site through other access ports created by the surgeon.
The insufflation gas is forced into the surgical site such as the abdominal cavity under pressure by an insufflation device. A number of insufflation devices have two modes of operation, initiation mode and maintenance mode. The initiation mode pumps gas at a high rate in order to quickly distend the pneumoperitoneum. In the maintenance mode, the insufflation gas is pumped at a rate up to a maximum pressure to replace the amount of gas lost during the procedure. Many insufflation devices are capable of delivering a maximum flow rate of approximately 16 to 25 liters per minute.
The maintenance pressure held at the surgical site by the insufflation device will vary depending on the insufflation gas and the patient""s weight for example. An obese patient will require a higher abdominal pressure in order to distend the pneumoperitoneum the same distance as that of a thinner patient.
Immediately after the pneumoperitoneum is first distended, an endoscope coupled to a television monitor is inserted into the abdominal cavity to visualize the interior of the surgical entry. In the case that the insertion of the trocar penetrates or punctures a major blood vessel, medical intervention including conventional invasive surgery may be required to control the hemorrhaging.
In the absence of exigent circumstances, the endoscope remains in the portal which is conventionally dedicated for that instrument. Additional portals are created to provide access for other surgical instruments including probes and other surgical devices that are individually inserted through other cannulas.
Lasers, electrocautery devices, and ultrasonic scalpels are often used during surgery to cut, cauterize, ablate, or vaporize tissues inside the abdomen. The application of the devices create xe2x80x9csurgical smokexe2x80x9d in the distended cavity as an unintended though not unexpected byproduct. Surgical smoke generally refers to gases or aerosols that may contain toxins, particulate matter, irritants, viable cells and viruses, water vapor, and other undesirable contaminants. Inside the abdominal cavity, the surgical smoke present a health risk to the patient and complicates the surgical procedure. In particular, the surgical smoke may be absorbed by the patient through the pneumoperitoneum and will obscure the surgeon""s visibility of the surgical field. Outside the patient, the smoke poses a health risk to the surgical personnel if not properly filtered.
There are a number of prior art devices for evacuating the surgical smoke from the cavity and filtering any gases discharged into the surgical room. Some of these prior art systems for smoke evacuation use a smoke filter in combination with an external source of vacuum used to draw the smoke laden insufflation gas from the surgical site through the filter. The source of vacuum may be provided by a wall outlet available in the surgical rooms or a dedicated machine capable of regulating the fluid flow rate though the filtration system. Smoke evacuation systems using a wall vacuum are unsuitable for most surgical applications because they require lengthy and obtrusive rubber hoses running from the patient and periodic intervention by the surgeon to balance the flow of insufflation gas pumped into or aspirated from the patient. The second class of smoke evacuation systems, including stand-alone and dedicated machines, requires a substantial capital investment to both purchase and maintain the equipment.
Still another category of prior art smoke evacuation systems includes strictly passive filtration systems that avoid the use of vacuum. U.S. Pat. No. 6,110,259 to Schultz and PCT application no. PCT/US99/28204 to Booth, which are both incorporated in their entirety by reference, operate solely in response to the pressure differential created by the surgical site and ambient air.
Schultz discloses a smoke filter and fluid conduit operatively coupled to a pressurized surgical site wherein the fluid flow rate is determined by the inherent properties of the filter media and the xe2x80x98substantially unobstructed fluid flow pathxe2x80x99 through the fluid conduit. As an advantage, Schultz asserts that his invention eliminates the dependency on a vacuum source and combination of xe2x80x98flow restrictors or reducersxe2x80x99 and filters. Moreover, the Schultz smoke evacuation system consisting only of a filter and fluid conduit teaches away from the use of multiple, in-line structures (filters, resistors, etc.) for stepping or reducing suction whose presence would avoid the simplicity cited as an advantage.
Notwithstanding the fluid regulatory properties of the filter media, the Schultz smoke evacuation system requires a stopcock to start and stop the fluid flow through the system. The stopcock remains in the closed position prior and during the application of the laser, electrocautery device, or ultrasonic scalpels, thereby preventing the escape of any smoke from the surgical site. The stopcock is only opened after the surgical site becomes has saturated with smoke that visibility is impaired. The stopcock is then turned to the full open position, at which point the pneumoperitoneum is rapidly deflated and the surgical smoke passed through the filter. Prior to any further surgery, the stopcock is again closed and the pneumoperitoneum re-pressurized by insufflation device, which may take uncomfortably long period of time. The process of evacuating the smoke and reinflating the pneumoperitoneum may be repeated numerous times during the laparoscopic procedure.
A significant disadvantage of the Schultz system is that the ability of the surgeon to visualize the surgical site and proceed with surgery is significantly hampered during the period that the smoke is evacuated and the pneumoperitoneum distended again. Not only is it inconvenient, but is poses a risk to the patient. More specifically, the surgeon is prevented from observing or intervening on behalf of a patient that is experience internal hemorrhaging, for example, while repeatedly inflating and evacuating the pneumoperitoneum.
Booth discloses a flow control device interposed between the surgical site and the smoke evacuation filter. Although the character of the flow control device is unspecified it would appear to be a form of stopcock consistent with the mechanism shown by Schultz. As such, the Booth device suffers the same drawbacks as the Schultz invention.
The present invention overcomes the limitations of the prior art with a fluid flow regulator which, when operatively integrated into a passive smoke evacuation system, regulates the flow rate to permit the continuous evacuation of surgical smoke without deflating the pressurized surgical site. The optimal evacuation flow rate, which is approximately 0.5 to 6.5 liters per minute, maintains the pneumoperitoneum in a distended position continuously through the duration of the laparoscopic procedure, permitting the surgical procedure to be conducted without interruption necessitated by deflation of the pneumoperitoneum used to smoke evacuation and subsequent reinflation.
The fluid flow regulator of the present invention is comprised of (i) a flow regulating means for providing a predetermined resistance to the flow of fluid, the appropriate resistance determined as a function of system variables including the resistance of the filtration system and (ii) at least one fluid conduit connecting means for coupling the flow regulating means to the smoke filtration system. The fluid flow regulator may be coupled to the downstream side of the smoke filtration system or, alternatively, between the filter and the surgical site.
In some embodiments, the flow regulating means is comprised of a diaphragm with at least one orifice of predetermined diameter, the diameter of the orifice restricting the flow of gas expelled from the surgical site within a range sufficient to effectively evacuate surgical smoke without deflating the pneumoperitoneum. The fluid flow regulator may be detachable from the smoke filtration system, thereby allowing one to select the flow regulator of appropriate resistance without replacing the filter itself. In other embodiments, the flow regulating means includes means for attaching a suction device to accelerate the evacuation of smoke when desirable.
In some embodiments, the orifice has an effective diameter of 0.5 to 5 millimeters, although this is subject to vary depending on the fluid flow resistance provided by the other components of the smoke evacuation system, namely the diameter of the cannula, the length and diameter of any conduits, and the resistance afforded by the filtration system itself.
In still other embodiments, the fluid flow regulator includes a system of flow regulating means which may include, for example, a plurality of differently sized orifices which may be operatively coupled to the filtration system to provide an optimal fluid flow independent of the system variables. The system variables that may influence the selection of the proper orifice include the pressure at the surgical site, the insufflation gas, the amount of smoke generated, the resistance provided by the various components of the evacuation system. In some embodiments, the plurality of orifices may be integrated into a single article of manufacture or apparatus to provide versatility and convenience to the surgeon.
The invention may also be characterized by a novel combination of steps. The method of using a fluid flow regulator in a minimally-invasive surgical procedure is comprised of the steps of (i) selecting the appropriate fluid flow regulator in consideration of the limitations described herein; (ii) operatively coupling the fluid flow regulator and smoke filtration system to a surgical site; (iii) pressurizing the surgical site with insufflation gas to distend the pneumoperitoneum; (iv) maintaining the distension of the pneumoperitoneum at a substantially constant position during the surgical procedure by simultaneously replenishing the surgical site with insufflation gas and continuously evacuating insufflation gas and/or surgical smoke through the smoke filtration system at a fluid flow rate substantially equal to the rate for replenishing the surgical site; and (v) evacuating the insufflation gas and surgical smoke at the conclusion of the minimally-invasive surgical procedure.
According to the method of the present invention, the fluid flow regulator may be used to limit or otherwise regulate the flow of fluid from the surgical site to fundamentally alter practice of laparoscopic surgery. In particular, application of the fluid flow regulator allows surgical smoke to be continuously evacuated from the surgical site without the need to interrupt the procedure to deflate the pneumoperitoneum and remove smoke. This additional step present in prior art systems prolongs the procedure and puts the patient at unnecessary risk for the period of time necessary to re-inflate and reestablish visual contact with the surgical site.
Therefore, the present invention reduces the risk to patients, reduces the time necessary to perform surgical procedures, reduces unnecessary manipulation of the smoke evacuation system as compared to prior art systems, namely Schultz and Booth. Also, the present invention provides a truly passive pressure maintenance system with little or no intervention or adjustment necessary by operating personnel.